Many conventional radio communication systems, such as paging systems, comprise a terminal/controller for gathering information and a plurality of base stations coupled thereto for receiving the gathered information and subsequently transmitting the information at a predetermined radio frequency over predetermined geographic areas. Thereafter, portable radio devices included in the system receive and decode the radio frequency signals to recover therefrom the transmitted information. This information can thereafter be presented to a user in a variety of ways. A portable device may, for example, use a display to visibly present information or a transducer to audibly present information. However, during transmission both to and from the base station, errors can occur in the information due to fading of the signal or due to interference. When this occurs, the user of the portable device may be presented with erroneous information, i.e., incorrect messages.
In digital communication systems, error correction techniques have been developed by which a base station can detect and correct a limited number of errors in each codeword of information provided thereto by the terminal/controller. In systems which use these error correction techniques, the terminal/controller typically generates parity information associated with and dependent on the message information included in each codeword of information. The amount of parity information which is included determines the number of errors which a base station will be able to subsequently detect and correct prior to forwarding the information to the portable radio devices. When the base station receives the signal, the parity information and the message information is recovered for each codeword. Thereafter, the parity information is used to verify and correct, if possible, the message information for each codeword. The message information is then encoded using a well known paging format and transmitted to the portable devices as a radio frequency signal.
Error correction techniques, however, generally require that each bit of each received codeword be processed individually using known error correction algorithms to verify the bit of information. As a result, conventional error correction techniques are usually very processor intensive, i.e., very time consuming. As a result, the amount of data which can be quickly processed and forwarded for transmission from the base stations to the portable devices is limited by the time required for error correcting the data. This is very undesirable because the transmission of information to portable devices, and therefore to the users, can be delayed.
Thus, what is needed is a method and apparatus for reducing the processing time necessary for error correction of information in a radio communication system.